Free FILE* and buffer from util.c process_lines()

This feels really messy, although the actual diff is relatively small.  It's
primarily icky because it involves the callback configfile_helper(), which can
invoke bsdtar_errc().  According to the comment for process_lines(), the
callback is supposed to return 0 or non-zero.  But since configfile_helper()
or dooption() is exiting upon error instead of returning, process_lines()
can't clean up after itself.

My thought right now is that a better fix would involve a much larger change
to libarchive code, but I'm open to other ideas.

tar/bsdtar.c

@@ -170,6 +170,8 @@ bsdtar_init(void)
 	bsdtar->conffile = NULL;
 	bsdtar->conf_opt = NULL;
 	bsdtar->conf_arg = NULL;
+	bsdtar->conffile_actual = NULL;
+	bsdtar->conffile_buffer = NULL;
 
 	/* We don't have bsdtar->progname yet, so we can't use bsdtar_errc. */
 	if (atexit(bsdtar_atexit)) {
@@ -199,6 +201,12 @@ bsdtar_atexit(void)
 	free(bsdtar->conf_opt);
 	free(bsdtar->conf_arg);
 
+	/* Free file-parsing variables from util.c. */
+	free(bsdtar->conffile_buffer);
+	if ((bsdtar->conffile_actual != NULL) &&
+	    (bsdtar->conffile_actual != stdin))
+		fclose(bsdtar->conffile_actual);
+
 	/* Free matching and (if applicable) substitution patterns. */
 	cleanup_exclusions(bsdtar);
 #if HAVE_REGEX_H

tar/bsdtar.h

@@ -132,6 +132,8 @@ struct bsdtar {
 	char		 *conffile;
 	char		 *conf_opt;
 	char		 *conf_arg;
+	FILE		 *conffile_actual;
+	char		 *conffile_buffer;
 
 	/* Used for --dryrun with tarsnap.conf.sample with a missing keyfile. */
 	int		  config_file_keyfile_failed;

tar/util.c

@@ -311,10 +311,18 @@ process_lines(struct bsdtar *bsdtar, const char *pathname,
 		f = fopen(pathname, "r");
 	if (f == NULL)
 		bsdtar_errc(bsdtar, 1, errno, "Couldn't open %s", pathname);
+
+	/* Record pointer for freeing upon error. */
+	bsdtar->conffile_actual = f;
+
 	buff_length = 8192;
 	buff = malloc(buff_length);
 	if (buff == NULL)
 		bsdtar_errc(bsdtar, 1, ENOMEM, "Can't read %s", pathname);
+
+	/* Record pointer for freeing upon error. */
+	bsdtar->conffile_buffer = buff;
+
 	line_start = line_end = buff_end = buff;
 	for (;;) {
 		/* Get some more data into the buffer. */
@@ -381,6 +389,11 @@ process_lines(struct bsdtar *bsdtar, const char *pathname,
 	free(buff);
 	if (f != stdin)
 		fclose(f);
+
+	/* Memory has been freed. */
+	bsdtar->conffile_actual = NULL;
+	bsdtar->conffile_buffer = NULL;
+
 	return (ret);
 }